<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>留言板</title>
  <style>
    .container {
      width: 350px;
      height: 300px;
      margin: 0 auto;
      /* border: 1px black solid; */
      text-align: center;
    }

    .grey {
      color: grey;
    }

    .container .row {
      width: 350px;
      height: 40px;

      display: flex;
      justify-content: space-between;
      align-items: center;
    }

    .container .row input {
      width: 260px;
      height: 30px;
    }

    #submit {
      width: 350px;
      height: 40px;
      background-color: orange;
      color: white;
      border: none;
      margin: 10px;
      border-radius: 5px;
      font-size: 20px;
    }
  </style>
</head>

<body>
<div class="container">
  <h1>留言板</h1>
  <p class="grey">输入后点击提交, 会将信息显示下方空白处</p>
  <div class="row">
    <span>谁:</span> <input type="text" name="" id="from">
  </div>
  <div class="row">
    <span>对谁:</span> <input type="text" name="" id="to">
  </div>
  <div class="row">
    <span>说什么:</span> <input type="text" name="" id="say">
  </div>
  <input type="button" value="提交" id="submit" onclick="submit()">
  <!-- <div>A 对 B 说: hello</div> -->
</div>

<script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.6.4/jquery.min.js"></script>
<script>

  function submit(){
    //1. 获取留言的内容
    var from = $('#from').val();
    var to = $('#to').val();
    var say = $('#say').val();
    if (from== '' || to == '' || say == '') {
      return;
    }
    //2. 构造节点
    var divE = "<div>"+from +"对" + to + "说:" + say+"</div>";
    //3. 把节点添加到页面上
    $(".container").append(divE);

    //4. 清空输入框的值
    $('#from').val("");
    $('#to').val("");
    $('#say').val("");

  }

</script>
</body>

</html>